This invention relates to a surface winder with recycled mandrels and method and,, more particularly, to a surface winder wherein the web is enveloped directly around the mandrel so as to develop, in effect, a "coreless" log of convolutely wound material.
The invention is to provide a winder which employs "free" mandrels which are pulled out of the finished log and thereafter recycled into the winding process. Recirculated mandrels have been used for a long time--see U.S. Pat. No. 3,148,843.
The main objective of the invention is to produce a wound product without separate core material. It is also desirable to have a hole in the center of the product so that a variety of dispensers can be used. The hole is preferably small, in the range of 0.375 inches (about 10 mm) to 0.750 inches (about 20 mm), so that the rolls cut from the log are stable. By stable, we mean that the wound structure will not collapse or unravel internally during cutting, packaging, shipping, etc. Larger holes tend to require a "fixing agent" to stabilize the area near the "core".
Another objective is to wind these products in a high speed, continuous manner. Currently the products are wound onto free mandrels but in a start/stop operation. These winders are typically limited in production due to the need to decelerate the entire line (unwind, embosser, rewind) to zero web speed during the transfer process.
Typical center winder technology also does not respond to this need because the small diameter mandrels would not have adequate stiffness to rotate at high speeds. For a 100 inch (2.5 meters) wide winder running at 2,500 FPM (800 mpm) the minimum mandrel diameter is about 1.5 inches (38 mm). Hence, the combination of production requirements and small hole size negate the center winding option.